<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		.box{
			width: 10px;
			height: 100px;
		}
		.img1{
			display: block;
		}
		.img2{
			display: none;
		}
	</style>
</head>
<body>
	<div class="box">
		<img src="../day02/image/02.jpg" alt="" class="img1">
		<img src="../day01/image/down.jpg" alt="" class="img2">
	</div>
</body>
<script src="../jquery-3.3.1.min.js"></script>
<script>
	
	var box = $(".box");


	box.mouseover(function(){

		$(".img2").css("display","block");

	})

	box.mouseout(function(){

		$(".img2").css("display","none");

	})
</script>
</html>